Transcript Slide 1
Green Your Machine: The Physics of More Efficient Computers and Cell Phones See the notes in the PPT file for ~script. Micky Holcomb Condensed Matter Physicist West Virginia University http://community.wvu.edu/~mbh039/ [email protected] Progress Through Size 1950s Shortening the Race = Faster Doubling (Moore’s Law) ~ Every 2 years, 2 Twice>200 as many Today, million transistors canfitfitoninthe the transistors can same head ofspace a pin! 12 years later With the same cost! By 2050 - if trends continue - a device the size of a micro-SD card will have storage of ~ 3x the brain capacity of the entire human race! What is Electricity? In some materials (metals), these electrons move freely under an applied voltage. 1) Making Them Smaller In a transistor, a voltage on the metal can induce flow of electricity between the two other contacts called the source (In) and drain (Out). In Voltage (C) Out Metal Insulator B A Silicon Area Speed Area Electron flow Thickness Electron flow The flow of electricity is affected by: properties of the insulator, the area of A&B and the insulator thickness Quantum Tunneling?!? Electrons are lazy! If the hill isn’t too wide, they tunnel through it. Not good. 2) Replacement Oxides • Insulating properties (resists electron flow) • “Plays nice” with current Si technology (temperature and quality) Many materials have been tried but none are as cheap and easy to manipulate as existing SiO2. 3) Strain Industry found that it could improve electron travel by straining (essentially squeezing) silicon. Strain can allow quicker, more efficient transfer of electrons. Reaching the Limits 1) Scaling 2) Replacements 3) Strain We are reaching the limit that these strategies can continue to improve technology. 4) Different Approach: Magnetism Using Magnetism 0 0 1 Problems with Magnetic Fields Magnetic field Require a lot of power Heating problems Difficult to localize – limits size Electrical Control of Magnetism Materials with strong coupling between electricity and magnetism at room temperature are rare - Simple idea: Grow a magnetic material on top of an electric material - Problem: the physics at boundaries is not yet well understood Pulsed Laser Deposition (PLD) Chamber base Modern growth techniques make fabrication of such structures possible! Our “Laser” Femtosecond pulses, one million times smaller than nanoseconds! Power of a laser pen: 5 mW Power of our lab’s laser: 1500 mW Paper will burn at 95 mW Cooling Down the Physics Antarctica reaches temperatures of Cryostat: where the material is -129°F Capable of reaching temperatures of -450°F This is just above ABSOLUTE ZERO, the coldest possible temperature. Other cool features: Low vibration stage Sample rotation Measurements Elsewhere Experiments At National Labs: X-ray Absorption Spectroscopy Photoemission Electron Microscopy (PEEM) Electric Control of Magnetism Before Grey (up) magnetic layer First E switch electric layer underneath Average direction Black (right) Arrows indicant direction of magnetism (0 or 1) Second E switch Summary Basic physics research has allowed significant progress in computing and other modern day technologies. As computers continue to get smaller, the physics becomes more interesting. Magnetic Electric Magnetoelectric materials offer a pathway to new devices. Magnetic and ferroelectric materials can be imaged and studied at WVU and national laboratories. Magnetic domains can be changed by an electric field. This work is funded by Our Science Superheroes A few of my collaborators: Left to Right: Srinivas Polisetty (post-doc), Disheng Chen (grad), Jinling Zhou (grad), Evan Wolfe (undergrad), Micky Holcomb (advisor) and National Chiao Tung University (Taiwan) Charles Frye (undergrad)